GB1338552A - Internal combustion engines - Google Patents

Abstract

1338552 Ignition timing of I. C. engines BIRMINGHAM SMALL ARMS CO Ltd 10 Dec 1970 [13 Dec 1969] 60901/69 Heading G1N [Also in Division H3] The ignition timing of an I. C. engine is determined by the phase relationship between a pulse train derived from the ignition pulses and a train of pulses coincident with the top dead centre position of the crank shaft, derived from an external rotating part. As shown Fig. 2, the ignition pulse train is obtained from a potentiometer 10 across the contact breaker 3, the pulses being shaped at 7 and fed to one input 8 of a phase comparator 9. The timing pulse train is obtained from a pick-up 11 associated with a slot in the periphery of the engine flywheel, coinciding with top dead centre, and is fed to another input 14 of the comparator 9. A train of reset pulses is also derived from the ignition pulse train and fed to reset terminal 17 of comparator 9. The latter comprises two bi-stable multi-vibrator circuits G1, G2 and G3, G4. Each is independently triggered by an ignition pulse and a timing pulse respectively, and both are reset by a reset pulse. During the interval between the ignition and timing pulse, current flows through meter 15 and its mean value is proportional to the "advance" or "retard' angle, as determined by the polarity of the current.